The present invention relates to coating compositions which provide films, such as adhesive release films and protective films, having improved water resistance, to a method for coating a substrate therewith and to a method for preparing stable emulsion forms thereof.
More particularly the present invention relates to coating compositions comprising a silicon-free, film-forming organic polymer and a liquid silicone resin which provide a film having the strength of the organic polymer and the water resistance of the silicone resin.
The liquid silicone resin which is used in the compositions and methods of this invention has been disclosed by J. D. Blizzard and T. J. Swihart in U.S. Pat. No. 4,310,678.
The liquid silicone resin component has further been mixed with certain vinyl- and/or hydroxyl-containing polydiorganosiloxane fluids to provide curable silicone compositions, as disclosed by J. D. Blizzard in U.S. Pat. No. 4,322,518. The curable silicone compositions of Blizzard are useful for coating a substrate. For example, a paper substrate is coated to provide a selectable-force adhesive release coating thereon.
While the compositions of Blizzard are useful for providing a selectable-force adhesive release coating, said force is in the premium to moderate force range, i.e., in the range of 20 to 50 N/m. Although a premium to moderate release force is highly desirable, higher release forces are also desired.
The compositions of Blizzard have the disadvantage that they are relatively expensive, compared to organic polymer-based coating compositions.
Film-forming organic polymers, such as poly(vinyl alcohol) and poly(styrene-co-butadiene), are relatively inexpensive compared to silicone polymers; however, they often lack the water resistance of silicone films.